(1) You can use Fluent Data Loader: an "add on" available from Amtec (free for Tecplot 8 users) which enables direct loading of *.cas and *.dat files into tecplot - meaning all geometry and solution features. This method saves memory space and your time, but then things are rather difficult to sort out inside Tecplot

(2) You can use Export panel in Fluent, choosing Tecplot option and saving specific variables on specific zones or surfaces. The data is saved in tecplot format which then can be opened in tecplot and dealt with in a usual way.

(3) There is another add on tool for tecplot - CFD Analyzer 2.0 (i'm afraid it is not free, but for tecplot users Amtec gives discounts) - with this tool you can use your fluent data to compute lots of derived quantities.

According to the vendor the FLuent Data Loader is available for Intel Windows and Alpha Windows. You can visit http://www.amtec.com -> Products -> Free Tecplot Add-ons and download relevant executable.